3D vector method of inter-field motion detection

Abstract

A method and apparatus are provided for displaying a progressive scan television signal derived from interlaced fields of a television signal. A colour space vector is derived for a current pixel and for each of at least two adjacent pixels within at least one field. A difference value between the current pixel colour space vector and each of the at least two adjacent pixel colour space vectors is then derived and used to determine whether motion is present at the current pixel. An appropriate method to derive the progressive scan image is then selected in dependence on the result of the determination.

1. A method for displaying a progressive-scan television signal derived from interlaced fields of a television signal, comprising the steps of:
 deriving a colour space vector for a current pixel; 
 for each of at least two adjacent pixels from at least one adjacent field, deriving difference vectors between the current pixel colour space vector and colour space vectors for each of the at least two adjacent pixels; 
 determining from the difference vectors whether motion is present at the current pixel by deriving a dot product of the difference vectors and determining whether the resultant dot product value exceeds a predetermined threshold; and 
 selecting a method to derive the progressive scan image in dependence on the result of the determination. 
 
     
     
       2. A method according to  claim 1  in which the adjacent pixels are vertically adjacent pixels. 
     
     
       3. A method according to  claim 1  in which the determining step includes the step of determining whether motion is present on a predetermined number of adjacent pixels. 
     
     
       4. A method according to  claim 3  in which the adjacent pixels are horizontally adjacent pixels. 
     
     
       5. A method according to  claim 1  in which the step of selecting a method for displaying the progressive scan image selects different methods for different areas of the display. 
     
     
       6. A method according to  claim 1  in which the step of selecting a method for display of the progressive scan image comprises selecting between an image comprising a pair of adjacent woven fields and an image comprising an interpolated image. 
     
     
       7. An apparatus for displaying a progressive scan television signal derived from interlaced fields of a television signal, comprising:
 colour space vector deriving means for deriving a colour space vector for a current pixel and for each of at least two adjacent pixels from at least one adjacent field; 
 difference vector deriving means for deriving difference vectors between the current pixel colour space vector and each of the at least two adjacent colour space vectors; 
 motion determining means for determining from the difference vectors whether motion is present at the current pixel, comprising:
 means for determining a dot product of the difference vectors, and 
 means for determining whether the resultant dot product value exceeds a predetermined threshold; and 
 
 method selecting means for selecting a method to derive the progressive scan image in dependence on the result of the determination. 
 
     
     
       8. Apparatus according to  claim 7  in which the adjacent pixels are vertically adjacent pixels. 
     
     
       9. Apparatus according to  claim 7  in which the motion determining means comprises means to determine whether motion is present on a predetermined number of adjacent pixels. 
     
     
       10. Apparatus according to  claim 9  in which the adjacent pixels are horizontally adjacent pixels. 
     
     
       11. Apparatus according to  claim 7  in which the method selecting means for selecting a method to derive the progressive scan image selects between different methods in different areas of the display. 
     
     
       12. Apparatus according to  claim 7  in which the method selecting means selects between an image comprising a pair of adjacent fields woven together and an image comprising an interpolated image. 
     
     
       13. A method for detecting motion at a current pixel in one of at least two adjacent fields of an interlaced video signal, comprising the steps of:
 deriving a colour space vector for the pixel; 
 deriving colour space vectors for at least two adjacent pixels from at least one adjacent field; 
 deriving difference vectors between the current pixel colour space vector and the at least two adjacent pixel colour space vectors; 
 determining from the difference vectors whether motion is present at the current pixel, comprising the sub-steps of deriving a dot product of the difference vectors, and determining whether the resultant dot product value exceeds a predetermined threshold; and 
 selecting a method for deriving a progressive-scan video signal from the interlaced video signal in dependence on the determination of whether motion is present at the current pixel. 
 
     
     
       14. An apparatus for detecting motion at a current pixel in one of at least two fields of an interlaced video signal, comprising:
 colour space vector deriving means for deriving a colour space vector for the current pixel and for at least two adjacent pixels from at least one adjacent field; 
 difference vector deriving means for deriving difference vectors between the current pixel colour space vector and the at least two adjacent colour space vectors; 
 motion determining means for determining from the difference vectors whether motion is present at the current pixel, including means for determining a dot product of the difference vectors and means for determining whether the resultant dot product value exceeds a predetermined threshold and 
 method selecting means for selecting a method for deriving a progressive-scan video signal from the interlaced video in dependence on the determination of whether motion is present at the current pixel.